The other day I ran into something on an audio record that I had never heard before. The recording produced either nothing, or in parts, a muffled echoed of the source that sounds as if it was recording only an echo effect.
Here's the setup:
We receive 2 channels from audio, which we run into an ARX MAXISPLIT.
We send a left and a right to two KiPro's, a left and a right to a DVD record, and the left to a local monitor.
We also loop out of one of the KiPro's to a Monarch USB recorder via HDMI.
All of the test records were fine, the only thing that changed inbetween were perhaps some level adjustments, and perhaps they changed the desk to the support act setup.
Both the DVD and the USB record exhibited this strange silenced record (we did not roll records on the KiPro's for that act). The monitor produced good audio the whole time, we could see level meters on the KiPros were solid the whole time.
Thinking about the signal flow the problem must arise either from the MAXISPLIT or the initial send. My first thought was the the record had been phase cancelled somehow, but looking at the file in post, it appears not. Please correct me if I'm wrong, but if a left and right of a recording is phase cancelled, then individually they should be fine right?
My only other thought is that there is a problem with the initial send.
I think you have it right. Perhaps the feed to you suffered form reversed polarity.
This is not impossible and could have happened by simply using one mis-wired audio cable anywhere along the chain you describe.
If you still have that source setup, check by feeding it into a device that has the ability to monitor in mono. If it sounds OK in stereo but sounds like you described in mono, you have found the problem.
You may be able to fix this by bringing the bad audio into a DAW and reversing the polarity of one of the two tracks.